1. Field of the Invention
The present invention relates to novel propylene resin compositions having excellent physical property balance (high heat resistance and impact strength at low temperature), injection molding processability, and paintability. The present invention relates to propylene resin compositions suitable for the material of a variety of industrial parts such as those of automobiles.
2. Background Art
Composite propylene resin compositions reinforced with components such as talc and a rubber have hitherto been used extensively for automobile parts such as a bumper, an instrument panel, a fan shroud, or a glove box, or for parts of domestic electric appliances such as a television, a VTR or a washing machine with making the best use of their excellent properties such as moldability, mechanical strength, paintability and profitability.
Recently, the level of required performances such as the formation of a molded part with a thinner wall or with a more complicated design has rapidly become higher in association with the higher facility of the aforementioned applications and the tendency of the products to become larger in size. For such tendency of the required performances to become larger, a variety of ideas have been proposed for the composite propylene resin compositions comprising polypropylenes, rubber components and talc such that the performance of an ethylene-propylene copolymer as the rubber components has been improved, or the talc particles have been made much finer.
However, little effective solutions have been proposed for improving the performance to a much higher level, for example the problem of exhibiting the performance which satisfies both high physical property balance (high heat resistance and impact strength at low temperature) and more excellent injection molding processability (especially, excellent fluidability and mold handling ability as well as good appearance of a molded product which hardly generates flow mark), while keeping excellent paintability which requires no degreasing treatment with trichloroethane which is usually carried out.